LOVE ET AL.: LIFE HISTORY AND FISHERY OF CALIFORNIA SCORPIONFISH 



Juveniles and Adults Collection 



Individuals used in the analysis of age and length, 

 length-weight, and reproduction were sampled 

 monthly (2-10 samples/month) from May 1981 to 

 June 1982 (and sporadically thereafter through May 

 1983). We used a 7.6 m (25 ft) or 4.9 m (16 ft) head- 

 rope otter trawl in 7-90 m of water, between Ven- 

 tura and San Onofre, CA. All specimens were frozen 

 for later dissection. After thawing, all fish were 

 measured (total length and standard length), 

 weighed, and sexed, and the gonads were removed 

 and weighed. 



Fish for food habit studies were taken by otter 

 trawl over soft substrata in 6-16 m of water between 

 Santa Monica Bay and San Onofre. These samples 

 were frozen immediately after collection. In the 

 laboratory, food items were identified to lowest 

 possible taxa, then weighed and counted. 



Techniques for Aging Juveniles 

 and Adults 



We attempted to age California scorpionfish by 

 a variety of calcified structures (sagittae, scales, 

 vertebrae, and pterygiophores) and found that cross 

 sections of anal pterygiophores gave best results. 

 The fused first and second anal pterygiophores 

 (supporting the first and second anal spines) were 

 removed from 613 specimens, cleaned, and stored 

 in paper coin envelopes. Pterygiophores were placed 

 on wood blocks and embedded in clear epoxy (Ciba 

 825 hardener and Ciba 6010 resin). Each block with 

 its pterygiophore was placed on a Buehler Isomet 

 low speed saw and an 0.05 cm wafer was cut through 

 it, using two diamond-edge blades separated by a 

 stainless steel shim. The cut was made near the 

 pterygiophore' s site of articulation with an anal 

 spine. Wafers were read under a compound micro- 

 scope at a magnification of 100 x , with both 

 reflected and transmitted light. All wafers were 

 read twice, by M. S. Love, approximately 6 mo 

 apart. When readings did not agree, they were read 

 again. The value of two coincident readings was ac- 

 cepted as the best estimate of age. 



We compared the age-length curves of males and 

 females using an analysis of variance of regression 

 coefficients over groups, testing the slopes of the 

 two curves (Dixon 1981). Parenthetically, this was 

 the same test used in comparing male and female 

 length-weight curves. Back calculations of length 

 on age were made using the techniques of Chen 

 (1971). 



Procedures for Determining 



the Timing of Maturation and 



Reproduction 



We estimated length at first maturity by classify- 

 ing gonads as immature or matured based on the 

 techniques of Bagenal and Braum (1971). Smaller 

 mature fish and fish just entering their first repro- 

 ductive season become reproductive later in the 

 year. Hence we estimated length at first maturity 

 from just before spawning season (March) through 

 its conclusion (August). A gonadosomatic index 

 [(gonad weigh t)/( total body weight) x 100] was com- 

 puted from frozen specimens to quantify changes 

 in gonad size with season. 



(W - GW) 

 We computed condition factor (100 x -, 



where W = body weight in grams, GW = gonad 

 weight in grams, and L = total length in centi- 

 meters), of mature California scorpionfish. Condi- 

 tion factor was computed using body weight with 

 gonad weight subtracted so as to minimize the ef- 

 fects of seasonal changes in gonad size. We com- 

 pared these values between seasons within sexes 

 and between sexes, using the Mann- Whitney U-Test 

 (Sokal and Rohlf 1969). 



Fishery 



To describe the California scorpionfish's role in 

 the commercial passenger vessel (partyboat) sport 

 fishery, we used the previously discussed Califor- 

 nia Department of Fish and Game creel census data. 

 We also examined the commercial fishery, inter- 

 viewing fishermen and utilizing the fish landing data 

 of the California Department of Fish and Game. 



RESULTS AND DISCUSSION 



Distribution and Movements 



Data from the Fish and Game creel census in- 

 dicated differences in abundance between the north- 

 ern and southern part of the Southern California 

 Bight (Fig. 1). Catch rates were lowest near the city 

 of Santa Barbara and generally increased to the 

 south. Highest catch rates occurred off San Diego 

 and around Catalina, San Clemente, and the Coro- 

 nado Islands. 



Utilizing the same data base, we examined Califor- 

 nia scorpionfish depth distribution (Fig. 2). Overall, 

 California scorpionfish were taken from barely sub- 

 tidal waters to 170 m. Depth distribution changed 

 with season. We plotted catch per unit effort in 6 



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